1. Field of the invention
This invention relates to a radiation image storage and reproduction system, and more particularly to a radiation image storage and reproduction system utilizing a stimulable phosphor sheet.
2. Description of prior art
A radiation image storage and reproduction method using a stimulable phosphor has been recently developed for replacing the conventional radiographic process. For instance, the radiation image storage and reproduction method is described in U.S. Pat. No. 4,239,968 and Japanese Patent Provisional Publications No. 55(1980)-12429, No. 55(1980)-87970, No. 55(1980)-103472, and No. 55(1980)-116340.
The stimulable phosphor absorbs and stores a radiation such as X-rays applied thereto and then emits the stored radiation energy in the form of a stimulated emission when it is irradiated with stimulating rays such as visible rays. The radiation image storage and reproduction method comprises the steps of causing a stimulable phosphor sheet (also referred to as radiation image storage panel or imaging plate) containing the stimulable phosphor to absorb radiation energy having passed through an object or having radiated from an object; sequentially exciting the stimulable phosphor with an electromagnetic wave such as visible rays or infrared rays (referred to as "stimulating rays") to release the radiation energy stored in the phosphor as light emission (stimulated emission); photoelectrically detecting the emitted light to obtain electric signals; and converting the electric signals into digital signals through analogue/digital (A/D) conversion. The obtained digital signals corresponding to the radiation image is optionally processed by one or more image processing methods, and reproduced as a visible image on a photographic material and/or stored in a memory means such as a magnetic tape or an optical disc.
Using the radiation image recording and reproducing method, a radiation image is obtainable with a sufficient amount of information by applying a radiation to an object at considerably smaller dose, as compared with the conventional radiography. Further, since the radiation image information can be directly obtained in the form of digital signals, various advantageous effects are attained. For instance, image processing such as gradation or contrast control processing can be readily performed; the image information can be reproduced in an optionally chosen form; and the information can be easily and reliably stored. Accordingly, this method is of great value in various radiographic processes, especially when the method is used for medical diagnosis.
The known radiation image recording and reproducing method is performed using various systems using several devices such as a radiation image read-out means for reading out a radiation image stored in a stimulable phosphor sheet to obtain digital image data of the radiation image; an image-concomitant information input means for inputting an information of forwarding address and/or an information (and optionally other data) of image processing operation for the digital image data; and image processing means for processing the digital image data; a display means for visually reproducing the radiation image from the digital image data; and an image filing means for storing the digital image data. Examples of the systems include an image reproducing system comprising a radiation image read-out apparatus, an image-concomitant information input apparatus, an image processing apparatus and a display apparatus; an image data storing system comprising a radiation image read-out apparatus, an image-concomitant information input apparatus, an image processing apparatus and an image filing apparatus; or a stored-image data out-put system comprising an image filing apparatus, an image processing apparatus and a display apparatus.